JPS59186221A - Switching controller of relay contact - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an opening/closing side of a relay contact and a control device that controls opening/closing of the relay contact near zero volts.

One type of proximity switch that controls the opening and closing of electrical circuits is a relay contact that uses electromagnetic operation.

When controlling the opening and closing of an AC circuit using this relay contact, conventionally the opening and closing of the relay contact has been controlled by, for example, other time settings, regardless of the instantaneous voltage of the AC power source. Therefore, if the instantaneous voltage of the AC power supply is high during the actual opening and closing of a relay contact, the voltage fluctuation dv/dt (v: voltage t: waiting time or current fluctuation d
i7. ．． Since t (1: current 12 hours) increases, noise is generated, which may cause malfunction of the electric circuit itself. Furthermore, applying high voltage and large current to the relay contacts naturally has a negative effect on the contacts, reducing the lifespan of the contacts. I kept it short.

This invention has been made in view of the above circumstances, and provides a low-noise, long-life relay contact by synchronizing the actual opening/closing timing of a relay contact that opens and closes an AC circuit with the zero-crossing timing of the AC circuit voltage. The purpose of the present invention is to provide a relay contact opening/closing control device that realizes the present invention.

That is, the present invention attempts to set the actual opening/closing timing of the relay contact by taking into consideration the mechanical operation time required for opening/closing the relay contact. Specifically, the invention attempts to set the actual opening/closing timing of the relay contact based on an external switching signal. When controlling the opening and closing of the relay, first, a zero-cross detection circuit detects each zero-cross of the AC voltage applied to the relay contacts.
A part of the detection output of the zero-crossing detection circuit is extracted based on the external switching signal, and the actual opening/closing timing of the relay contact is adjusted to match the zero-crossing timing of the AC voltage by delaying the extracted output by a predetermined time. I try to recycle it.

The following is a relay contact opening/closing control device according to the present invention? Embodiments will be described in detail according to embodiments shown in the accompanying drawings.

FIG. 1 shows an embodiment of a relay contact opening/closing control device according to the present invention.

In Fig. 1, l is a relay contact, 2 is a load, 3 is an AC power supply, 4 is a DC power supply, 5 is a coil that electromagnetically operates the relay contact l, 6 is a surge absorption diode, 7 is a switch element, and 8 is a zero cross Detection circuit, 9 is an AND circuit, 10
is a timer circuit. The zero cross detection circuit 8 detects this every time the voltage of the AC power supply 3 crosses the zero volt line, and outputs a signal of, for example, a logical level to one input terminal of the AND circuit 9.

An external input signal S is input to the other input terminal of the AND circuit 9, and the AND circuit 9 performs a logical product of these two input signals and adds this to the timer circuit 0. The timer circuit IO generates a switching signal by delaying each output of the AND circuit 9 by a predetermined time based on the mechanical operation time required to open and close the relay contact 1, and applies the switching signal to the switch element 7 to activate the switch. Turn on element 7. When the switch element 7 is turned on, the coil 5 becomes conductive, thereby closing the relay contact l.

Next, a concrete operation example of the embodiment device shown in FIG. 1 will be explained as follows.
This will be explained in detail with reference to the time chart shown in the figure.

The ff zero-cross detection circuit 8 constantly monitors the AC voltage applied to the relay contact 1, detects this every time the AC voltage crosses zero, and outputs a high-level signal with an appropriate width to the AND circuit 9. (See Figures 2(a) and (b)).

When closing a relay contact, an external input signal S that is at a high logic level for a time corresponding to the closing time is input to the other input terminal of the AND circuit 9 (second (See figure (C)). The AND circuit 9 extracts these two manual outputs, and from this, only the detection output corresponding to the external input signal S is extracted, and the first cough extraction signal is input to the timer circuit 10 (Fig. 2(d) )reference). The timer circuit 10 sends a switching signal to turn on the switch element 7 based on the output of the AND circuit 9.
(see Figure 2(e)). This switching signal
The switch element 7 is turned on by the signal, and the relay coil 5 is turned on.
A current flows through, and relay contact 1 is closed (Fig. 2 (f)
)reference). As a result, the voltage of the AC power supply 3 is applied to the load 2 (see Fig. 2 (g)) a Now, after the switching signal that is the output of the timer circuit IO rises, the relay contact 16'- There is a qualitative time lag before closing due to various factors, such as the mechanical operating time of the relay contact. Let this time difference be t2.

Therefore, in order to turn on the relay contact at the moment when the AC voltage h'' applied to the relay contact 1 crosses the zero volt line, the timer circuit 10 (1) is inputted with the output of the AND circuit 9, and then the timer circuit 10 is switched on. The delay time t1 until the signal is output can be set to t, + t, -nT (n: natural number, T: 100 cycles of AC voltage) (Figure 2 (e) (f) )reference),.

In addition, the time from when the output current of the timer circuit 10 falls to when the relay contact l returns is due to the factors mentioned above.
There is a more qualitative time lag.

Let this time difference be t4.

Therefore, in order to restore the relay contact at the point when the AC voltage applied to the relay contact 1 crosses the zero volt line, the switching of the timer circuit 10 must be started from the time when one output pulse of the AND circuit 9 is input to the timer circuit 10. The time until the signal falls (CT+t3) is (T
-)t, )→-t+=(n+i)'r Cn: Natural number T: AC voltage 07 cycles) In other words, it is sufficient to set the time t3 so that t8-1-t4==il T (the Figure 2 (e)
(see (f)).

By setting the delay time of the timer circuit 10 in this manner, even in the case of a relay contact that cannot be opened or closed instantaneously, it is possible to perform the opening and closing operation at near zero volts.

As explained above, 1. According to the relay contact opening/closing control device according to the present invention, since the relay contacts are opened and closed when the AC voltage crosses the zero volt line, a low-noise and long-life relay contact circuit is realized. can do.

[Brief explanation of drawings]

Jx diagram is a circuit block diagram showing one embodiment of the relay contact opening/closing control device according to the present invention, and FIG. 2 is a time chart showing an example of the operation of the embodiment device shown in FIG. 1. l... Relay contact, 2... Load, 3... AC power supply, 4... DC power supply, 5... Relay coil, 6...
Surge absorption diode, 7... switch element, 8...
・Zero cross detection circuit, 9...AND circuit, 10...
・Timer circuit

Claims (1)

[Claims] In a relay contact opening/closing control device that has a relay contact arranged to open and close an AC circuit and a relay drive circuit that opens and closes this relay contact based on an external switching signal, this a zero-crossing detection circuit for detecting a zero-crossing detection circuit; a logic circuit for ANDing the detection output of the zero-crossing detection circuit and the external switching signal; 1. A relay contact opening/closing control device comprising: a timer circuit that delays the output of a logic circuit for a predetermined period of time and applies the delayed output to the relay drive circuit.